Transcript Slide 1
Marisa Bernal Neysa Alicea Angélica Báez Beatriz Ramos if you loose any of your limbs? Outline Design Purpose Applications Engineering Considerations Uniqueness Challenges Areas of Opportunities New Techniques Prosthetic Leg LINER SOCKET KNEE FEET Socket Purpose Improve the design of the prosthesis socket, making it more comfortable for the user, and thus improving the quality of life of people with disabilities. Applications For medical purposes, related to athletes with disabilities. Engineering Considerations Use impact analysis in our calculations Use the safest approximations for our design Proper material selection Material Characteristics Lightweight low density Stiff high Elastic Modulus Minimize Maximize Material Characteristics Material Characteristics Material Possibilities Wood Technical Ceramics Composites Carbon Fiber Reinforced Plastics (CFRP) Carbon Fiber Reinforced Plastic (CFRP) Density: 1.8 g/cc Modulus of Elasticity: 225 GPa Sut: 3800 Mpa Uniqueness A prosthesis has to be designed to fit the needs of a specific person. It is customized for each user Challenge Consider that the product is a medical device Convert our project to shapes that we can analyze with the concept learned in class Material Selection Static Loads Analysis Static Load Analysis For this analysis we used the following equations and obtained the shown values. My KN 115 .8 2 I m 3V KN 4.62 2 2A m qx3 C1 x 2 1 ( x) C 2 x C3 2 6 EI (x ) 2.68 x 10-6m= 2.6 x 10-3mm Dynamic Load Analysis Dynamic Load Analysis Impact Load Maximum Elongation M=mass v=velocity at impact L=length E=Elastic Modulus A=area Dynamic Load Analysis Impact Load Maximum stress E = Elastic Modulus δmax = maximum elongation L = length Dynamic Load Analysis We calculated the values of: = Pmean amplitude = 128.69MPa = mean Pamplitude =3195.38KN Using stress concentrator factor Kf = 1.5 amplitude,SC = 192.95MPa mean,SC = 192.95MPa We calculated the fatigue strength: ' S f = 0.4 SUT ' S f =1520MPa Dynamic Load Analysis Stress concentration factors: K size 0.792 K load 0.85 K surface 0.7841 K termperature 1 K reliability 0.620 S f (0.792)(0.85)(0.7841)(1)(0.620) S f 497.5MPa Dynamic Load Analysis Using Modified Goodman theory to calculate the safety factor: n 1 vm,a vm,m S S f UT 1 192.95MPa 192.95MPa 497.5MPa 3800MPa 2.28 Component life Aproximated it to the behavior of aluminum Sm Sm Sf 1.3 x 107 5 x 108 a=19922.54, b= -0.2815 N = 1.3 x 107 cycles Areas of Opportunity Assumed values were used since data for our material was not available Design uniqueness. A different analysis is needed for each person New Knowledge Reinforce teamwork skills Loads distribution in prosthetic devices Impact loads Any Questions???